Self-propelled vehicles and machines such as riding lawn mowers, snow-throwers, and lawn or garden tractors using variable speed drives are well known. Such variable speed drives, whether hydrostatic, toroidal, friction, or the like, will generally have a control shaft whose rotation, via manipulation of an operator control mechanism mechanically linked to the control shaft, regulates the variable speed drive's output. As an example, many zero-turn mowers employ a pair of pumps which independently transmit hydraulic fluid, and thus power, to a corresponding pair of hydraulic motors, each independently driving a separate axle and wheel combination to provide steering. The control mechanism utilized by an operator of the machine often employs a damper to prevent sudden acceleration or deceleration of the machine resulting from unintended manipulation of the control mechanism, for example, when the operator is jostled upon striking a bump, dip, or other obstacle in the machine's path. Dampers may be used between the operator control levers and the frame or body of the zero-turn mower, using mounting points on the mower's body or frame distant from the variable speed drive system. Dampers may also be connected directly to a control arm, the mechanical link between the control shaft of the pump and the operator control mechanism. Again, additional mounting points are necessary to effectuate the damping effect.
It would be advantageous for manufacturers of self-propelled vehicles and machines to eliminate bulky dampers and their associated mounting points, reducing manufacturing costs and assembly complexity, while retaining the functional benefits of the dampers.